German Patent No. 3420917A1 describes a point-to-multipoint radio relay system. The German Patent mentioned that the central station possesses an antenna having either an omnidirectional characteristic, or a sector characteristic. To produce an omnidirectional characteristic which covers the entire area surrounding the central station, it is possible to work with a single antenna (dipole). Alternatively to that, the area surrounding the central station can be divided into individual sectors, a separate antenna being responsible for the illumination of each sector. These conventional antenna arrangements require a high transmitting power, both from the central station and the subscriber stations.